Hierarchically porous Zn2Ti3O8/ZnTiO3heterojunction aerogel for accelerated spatial charge separation and enhanced photocatalytic ofloxacin degradation

The persistent discharge of ofloxacin (OFL) into aquatic environments poses severe ecological threats. However, conventional titanium-based photocatalysts suffer from limited visible-light response and rapid charge recombination. Herein, self-supporting Zn 2 Ti 3 O 8 /ZnTiO 3 Type-II heterojunction aerogel was synthesized via a sol-gel pathway coupled with supercritical CO 2 drying and thermal modulation. Comprehensive XRD and HRTEM/SAED analyses confirm the synchronous crystallization of cubic Zn 2 Ti 3 O 8 and hexagonal ZnTiO 3 , establishing an intimate heterojunction interface. Meanwhile, SEM observation reveals a highly continuous 3D interconnected porous aerogel framework. Calcined at 750 ℃, the optimized aerogel beautifully preserves a hierarchically porous network with an expansive specific surface area, providing abundant active sites and fast mass transfer channels. Consequently, the heterojunction aerogel sample achieves an exceptional OFL degradation efficiency exceeding 96% within 60 min under simulated solar light, obeying pseudo-first-order kinetics. Photoelectrochemical profiling and ESR analyses verify that the staggered Type-II alignment robustly suppresses carrier recombination, accelerating charge separation to harvest active free radicals (·O 2 - and ·OH) for OFL mineralization. Furthermore, density functional theory (DFT) and frontier molecular orbital calculations corroborate the hybridized electronic structure and unveil the targeted radical attack pathways for molecular cleavage. This work provides a compelling paradigm to merge heterojunction chemistry with structural aerogel design for environmental remediation.